Is my spider a boy or a girl?

At some times in a spider’s life it is easy to tell whether it is a male or a female, but at other times it can be impossible. This is because the reproductive organs of a spider do not develop until the spider has reached maturity. Juvenile male and female spiders look almost exactly the same. As a spider grows, it sheds its skin, or moults, several times. The reproductive organs do not develop and become visible until after the final moult.

The most reliable character to use to distinguish male and female spiders is the position of the reproductive openings.

Female spiders

The female reproductive opening is located on the underside of the abdomen, near the front of the spider. It is called an epigynum and is often hardened and dark in colour.

Male spiders

The male reproductive system is a bit more complex. The testes are located on the underneath of the abdomen, and connect to the surface via a small tube. The male spins a small mat of silk and deposits a ‘packet’ of sperm from the testes onto the silk mat. He then syphons up this sperm packet into a reservoir, called an embolus, located in the last segment of his palps. This is why the palps of a mature male spider resemble tiny boxing gloves.

Comments (13)

The article on this page says, "Unlike insects and other organisms, male spiders do have a penis." Shouldn't there be a "not" in that sentence, so that it would read, "Unlike insects and other organisms, male spiders do NOT have a penis"?

Hi Zeppelin, huntsman spiders will take crickets. Regarding how to tell whether your spider is a boy or a girl it can be quite difficult as is explained higher up in this sheet. While the spiders are juveniles it is nearly impossible; but once they are adults have a look at the palps of the spider. For males the palps should be enlarged or modified, see the information given above. Have a look online at images of male and female adult huntsman spiders so you can get an idea of how the palps vary between the two sexes.

Jenny Paterson
17 October, 2014 15:13

I have a photo of a big slow old huntsman I was going to send you but the email address seems not to be working. Cheers Jenny